Only making full boost uphill under load. Why???
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
Only making full boost uphill under load. Why??? Ive been fighting with this boost issue for a little while. 3rd gear on flat road it will make 8-9 psi. Uphill it will make 12-13 psi. Waste gate has a 13 psi spring installed. Not sure what to check. At a local dyno night i had to brake boost it to make 10 psi.
Speed Daddy Ebay 44mm wastegate with a new diaphram bought separately. i tested it with my air compressor and it seemed to open around the right PSI (my regulator doesnt have great resolution.)
VS Billet 78/75 turbo
6.0
243 heads
~10.5:1
3.55 gears
camshaft https://www.howardscams.com/hydrauli...cams-190325-12
I took the reference off the gate, and it will spool instantly to 15 psi + by 3500 rpm before i let out. I understand the 13 psi spring doesnt mean ill make 13psi, with backpressure and all that. It depends on the efficiency of the setup.
Do i need more spring? If so, why does it make the correct 12-13 psi going uphill? I understand backpressure and all that makes the gate open at a certain point, not exactly at the rated spring pressure (13 psi in this case). I dont want to put more spring in it, then be going uphill and make even more boost on top of that. I tried compressor referencing the wastegate as well as referencing off the intake. No change.
Any ideas or suggestions? I'm sure its just my inexperience. Any help is appreciated. Ill attach log files and tune files.
Speed Daddy Ebay 44mm wastegate with a new diaphram bought separately. i tested it with my air compressor and it seemed to open around the right PSI (my regulator doesnt have great resolution.)
VS Billet 78/75 turbo
6.0
243 heads
~10.5:1
3.55 gears
camshaft https://www.howardscams.com/hydrauli...cams-190325-12
I took the reference off the gate, and it will spool instantly to 15 psi + by 3500 rpm before i let out. I understand the 13 psi spring doesnt mean ill make 13psi, with backpressure and all that. It depends on the efficiency of the setup.
Do i need more spring? If so, why does it make the correct 12-13 psi going uphill? I understand backpressure and all that makes the gate open at a certain point, not exactly at the rated spring pressure (13 psi in this case). I dont want to put more spring in it, then be going uphill and make even more boost on top of that. I tried compressor referencing the wastegate as well as referencing off the intake. No change.
Any ideas or suggestions? I'm sure its just my inexperience. Any help is appreciated. Ill attach log files and tune files.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
Bump. Combination of things? Backpressure, too small of a gate, and bad placement? Backpressure pushes gate open at 8-9 psi, too small of a gate can’t vent enough with more load going uphill, or bad placement can’t vent enough?
Boost doesn’t keep climbing when WOT uphill. It hits 12 ish psi, holds, and drops slightly at high rpm. That’s what makes me think the gate is ok. Just not sure why it doesn’t build boost on flat ground in 3rd. Don’t have many areas to test out 4th gear. 2nd gear makes 5-6 psi. Again, unhook the reference line and it will boost to 15 psi at half throttle on flat in 3rd. So confusing to me.
let me know if you guys have any ideas at all. Ordered a low resolution air regulator to see exactly what psi makes the gate open with 13 psi spring.
Boost doesn’t keep climbing when WOT uphill. It hits 12 ish psi, holds, and drops slightly at high rpm. That’s what makes me think the gate is ok. Just not sure why it doesn’t build boost on flat ground in 3rd. Don’t have many areas to test out 4th gear. 2nd gear makes 5-6 psi. Again, unhook the reference line and it will boost to 15 psi at half throttle on flat in 3rd. So confusing to me.
let me know if you guys have any ideas at all. Ordered a low resolution air regulator to see exactly what psi makes the gate open with 13 psi spring.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
vacuum tested all lines. Boost leak tested cold side. Smoke tested intake. All good.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
Restricted User
Joined: Mar 2014
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From: Ohio
Too many factors to make a real determination. You're juggling load, exhaust volume, crack pressure, backpressure, etc.
Typically, you'll almost always run less boost than what you're spring is rated for due to crack pressure and backpressure. With a large enough gate, it wouldn't have to fully open to bypass enough exhaust to keep boost from increasing. A 60mm gate only needs to open 40% to bypass more exhaust than a 38mm will fully open. The spring will begin to compress before its rated pressure, and you'll end up with less boost. Running the wastegate reference on the compressor housing makes it worse, as you'll see more boost there than in the intake (with an intercooler), so it'll open another couple of pounds less.
It could be that the up-hill boost is normal, and that the flat ground boost is reduced from the wastegate cracking open early and bypassing enough exhaust to prevent boost from climbing. The reason it wouldn't do this up hill is the increased exhaust volume still being enough to maintain turbo spool even with the gate cracked open. A manual ball/spring boost controller will fix this. You can set it so that you don't run any more boost than normal, but it'll prevent boost pressure from cracking the wastegate open too early.
Unfortunately, it could be 3 or 4 other things as well. At this point you're asking for theories. A backpressure gauge will be the only thing that can narrow it down.
Typically, you'll almost always run less boost than what you're spring is rated for due to crack pressure and backpressure. With a large enough gate, it wouldn't have to fully open to bypass enough exhaust to keep boost from increasing. A 60mm gate only needs to open 40% to bypass more exhaust than a 38mm will fully open. The spring will begin to compress before its rated pressure, and you'll end up with less boost. Running the wastegate reference on the compressor housing makes it worse, as you'll see more boost there than in the intake (with an intercooler), so it'll open another couple of pounds less.
It could be that the up-hill boost is normal, and that the flat ground boost is reduced from the wastegate cracking open early and bypassing enough exhaust to prevent boost from climbing. The reason it wouldn't do this up hill is the increased exhaust volume still being enough to maintain turbo spool even with the gate cracked open. A manual ball/spring boost controller will fix this. You can set it so that you don't run any more boost than normal, but it'll prevent boost pressure from cracking the wastegate open too early.
Unfortunately, it could be 3 or 4 other things as well. At this point you're asking for theories. A backpressure gauge will be the only thing that can narrow it down.
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Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
Too many factors to make a real determination. You're juggling load, exhaust volume, crack pressure, backpressure, etc.
Typically, you'll almost always run less boost than what you're spring is rated for due to crack pressure and backpressure. With a large enough gate, it wouldn't have to fully open to bypass enough exhaust to keep boost from increasing. A 60mm gate only needs to open 40% to bypass more exhaust than a 38mm will fully open. The spring will begin to compress before its rated pressure, and you'll end up with less boost. Running the wastegate reference on the compressor housing makes it worse, as you'll see more boost there than in the intake (with an intercooler), so it'll open another couple of pounds less.
It could be that the up-hill boost is normal, and that the flat ground boost is reduced from the wastegate cracking open early and bypassing enough exhaust to prevent boost from climbing. The reason it wouldn't do this up hill is the increased exhaust volume still being enough to maintain turbo spool even with the gate cracked open. A manual ball/spring boost controller will fix this. You can set it so that you don't run any more boost than normal, but it'll prevent boost pressure from cracking the wastegate open too early.
Unfortunately, it could be 3 or 4 other things as well. At this point you're asking for theories. A backpressure gauge will be the only thing that can narrow it down.
Typically, you'll almost always run less boost than what you're spring is rated for due to crack pressure and backpressure. With a large enough gate, it wouldn't have to fully open to bypass enough exhaust to keep boost from increasing. A 60mm gate only needs to open 40% to bypass more exhaust than a 38mm will fully open. The spring will begin to compress before its rated pressure, and you'll end up with less boost. Running the wastegate reference on the compressor housing makes it worse, as you'll see more boost there than in the intake (with an intercooler), so it'll open another couple of pounds less.
It could be that the up-hill boost is normal, and that the flat ground boost is reduced from the wastegate cracking open early and bypassing enough exhaust to prevent boost from climbing. The reason it wouldn't do this up hill is the increased exhaust volume still being enough to maintain turbo spool even with the gate cracked open. A manual ball/spring boost controller will fix this. You can set it so that you don't run any more boost than normal, but it'll prevent boost pressure from cracking the wastegate open too early.
Unfortunately, it could be 3 or 4 other things as well. At this point you're asking for theories. A backpressure gauge will be the only thing that can narrow it down.
Great explanation. Thank you for this.
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Verdad Gallardo Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
Sounds like i need a electronic boost controller. I was watching videos on the AEM truboost and you set the controller to your wastegate spring pressure, and it keeps the solenoid 100% open on the top of the gate until you reach that manifold pressure. then the boost controller takes over to regulate boost. They showed how a turbo would be laggy without this function enabled. Sounds exactly like what i need to help cure this problem. It would stop the waste gate from cracking open until the desired boost level was met. Like i said, it was probably my lack of experience. Thanks for all the replys.
TECH Apprentice
Joined: Apr 2012
Posts: 333
Likes: 4
From: New Zealand
That sounds definitely worth trying. I run an e-Boost2 and I'm convinced it also cracks the valves prematurely (not as bad as your though) then shuts allowing a 2psi spike right at TQ peak where you do not want it (detonation territory). I'm going to get a better boost controller
Teching In
Joined: Aug 2018
Posts: 4
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When you bench tested the wg with your air compressor could you hear air leaking through the gate before the valve cracked open? I’ve had a similar issue in the past with a leaky turbosmart hypergate, it caused slow turbo response. Funny enough I swapped it out for a $60 speed daddy gate that did not leak when bench tested and it fixed my issue. I’d suggest taking the wg apart and inspecting everything and make sure it doesn’t leak when bench tested.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
When you bench tested the wg with your air compressor could you hear air leaking through the gate before the valve cracked open? I’ve had a similar issue in the past with a leaky turbosmart hypergate, it caused slow turbo response. Funny enough I swapped it out for a $60 speed daddy gate that did not leak when bench tested and it fixed my issue. I’d suggest taking the wg apart and inspecting everything and make sure it doesn’t leak when bench tested.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
That sounds definitely worth trying. I run an e-Boost2 and I'm convinced it also cracks the valves prematurely (not as bad as your though) then shuts allowing a 2psi spike right at TQ peak where you do not want it (detonation territory). I'm going to get a better boost controller
TECH Enthusiast
Joined: Nov 2016
Posts: 711
Likes: 6
From: PNW
You clearly don’t understand how a turbo system works. The wastegate doesn’t vent to increase boost, it vents to DECREASE boost. If the gate is too small, you will get more boost or “boost creep.” The wastegate is to allow exhaust to bypass the turbo - that's why it’s mounted before the turbo. Your total confusion on how this works is probably your problem.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
You clearly don’t understand how a turbo system works. The wastegate doesn’t vent to increase boost, it vents to DECREASE boost. If the gate is too small, you will get more boost or “boost creep.” The wastegate is to allow exhaust to bypass the turbo - that's why it’s mounted before the turbo. Your total confusion on how this works is probably your problem.
I fabbed the system myself, not that im bragging. Just saying I understand how it works. Sorry if the question was worded in a way that was difficult to understand. Thank you for your concern and your reply.
Last edited by SiskMan; Oct 16, 2018 at 03:42 PM.
TECH Enthusiast
Joined: Mar 2013
Posts: 502
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You clearly don’t understand how a turbo system works. The wastegate doesn’t vent to increase boost, it vents to DECREASE boost. If the gate is too small, you will get more boost or “boost creep.” The wastegate is to allow exhaust to bypass the turbo - that's why it’s mounted before the turbo. Your total confusion on how this works is probably your problem.
Thread Starter
Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
A) not a big enough waste gate to vent adequately, causing creep
B) bad wastegate placement causing creep